Online conductivity monitoring: validation and usefulness in a clinical trial of reduced dialysate conductivity

ASAIO J. Jan-Feb 2005;51(1):70-6. doi: 10.1097/


Relatively low dialysate conductivity (Cndi) may improve outcomes by reducing the overall sodium burden in dialysis patients. Excess sodium removal, however, could lead to hemodynamic instability. We performed a randomized controlled trial of reduction of Cndi. For the study, 28 patients were randomized to maintenance of Cndi at 13.6 mS/cm (equivalent to 135 mmol/L of Na+) or serial reduction of Cndi in steps of 0.2 mS/cm, guided by symptoms and blood pressure. Sodium removal estimated from pre- and postplasma concentrations correlated well with removal measured by conductivity monitoring as ionic mass balance (R2 0.66, p < 0.0001). Of the 16 patients randomized to reduction of Cndi, 6 achieved Cndi 13.4 mS/cm, 6 achieved 13.2 mS/cm, and 4 achieved 13.0 mS/cm. No episodes of disequilibrium occurred. Interdialytic weight gain was reduced from 2.34 +/- 0.10 kg to 1.57 +/- 0.11 kg (p < 0.0001). Predialysis systolic blood pressure fell from 144 +/- 3 mm Hg to 137 +/- 4 mm Hg (p < 0.05). The reduction in convective sodium removal was balanced by an increase in diffusive sodium removal (95 +/- 9 mmol cf. 175 +/- 14 mmol, p < 0.0001). Reduction in Cndi monitored by IMB is safe and practical and leads to improved interdialytic weight gains and blood pressure control, while avoiding excessive sodium removal.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Pressure
  • Dialysis Solutions / chemistry*
  • Electric Conductivity*
  • Electrodes
  • Humans
  • Middle Aged
  • Monitoring, Physiologic
  • Renal Dialysis*
  • Reproducibility of Results
  • Sodium / blood*
  • Weight Gain


  • Dialysis Solutions
  • Sodium